This invention relates to an effective steering safety mechanism which assures safety when the driver of an automotive vehicle turns the steering wheel of the vehicle suddenly and sharply.
In a known conventional power steering system, the force for turning the steering wheel is applied by the driver with an assist from a hydraulic or electric motor. Such a steering system adjusts the amount of power assist for the steering wheel in dependence upon vehicle velocity and steering angle, taking into account both steerability and safety. Power assist is applied for steering at low velocities in order to lighten the load on the driver when the steering wheel is turned. At high velocities, however, the power assist is limited in order to prevent a loss of stability that can be caused by a steering wheel that turns too lightly.
In the conventional power steering system, however, the chief aim is to provide the power assist in order to make it easier for the driver to turn the steering wheel for turns made at low velocity. No consideration is given to restricting steering or to positive application of a restoring force when the vehicle skids sideways due to centrifugal force or when the steering wheel is turned so sharply as to risk overturning the vehicle, both of these possibilities at high traveling velocities.
Recently, electric automobiles have been developed in which the front and rear wheels are capable of being steered up to an angle of 90.degree. by electric motors so that the vehicle can make small turns or travel in translational fashion. When the steering wheel is turned to sharply and suddenly in such a vehicle, there is the danger that the vehicle will skid sideways or roll over unless steering is restricted or a restoring force applied in a positive manner.